It is known that with rotary vane pumps, and particularly with those types used in motor vehicles, the required lubricant may be supplied via a hollow portion formed axially within the drive shaft of the device in order to seal the vanes of the pump along the internal walls of the stator housing and to lubricate all of the moving parts thereof. The lubricant, usually motor oil, is guided under pressure into the hollow portion of the pump drive shaft from a passage formed in the driving motor shaft.
Ball bearings are utilized in such known devices for positioning the pump drive shaft within the pump housing. Although these bearings are also lubricated by the lubricant fed to the pump, particular attention has not been paid to controlling the supply of the lubricant to them. Therefore, with these former designs it was possible for the bearings to revolve for varying periods in spent lubricant since its circulation was not controlled throughout the system. Hence, as a result of this fact the life span of the individual bearings was quite variable and often very short.